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Formation of crystals in saturated and undersaturated solutions is studied as a result of intense sound, or shock waves, produced by high intensity focused laser pulses. Many tiny crystals are created immediately throughout the solution by the laser-generated sound waves. The compression waves can be created by focusing within the liquid or onto the walls of a container. This new method allows for the instantaneous formation of many “seed” crystals, which are then available for further impurity-free crystal growth. More importantly, the tiny “baby” crystals can be harvested before complete growth into “adult” crystals can occur. This method is shown to produce enough “baby” crystals to provide a glimpse into the initial stages of crystal growth using modern microscopy techniques such as SEM. By employing this new method, simple salts such as sodium bromate, sodium chloride, sodium chlorate, and tartaric acid were successfully crystallized. This method of crystal growth may also allow for the generation of...

As there are high demand in the quantum treatment of fiber-optic communication technologies, investigation of inherent quaantum noise in pulse propagation along a waveguide is essential. In this paper, we simulate the pulse propagation through an optical fiber in presence of the third order dispersion coefficient and show the amplitude errors of the propagated soliton. Finally, we compare our simulation results with those obtained when the second order dispersion coefficient is just considered.

Although electron beams with energies of a few keV can excite fluorescent X-ray production from solids, ion beams of comparable energy cannot do so. The reason for this situation is that it is the velocity of the incident particle, rather than its energy, which determines whether an ionization event can be generated. SCANNING 29: 1–4, 2007. Copyright © 2007 Wiley Periodicals, Inc.

Background: The control of leishmaniasis faces serious challenges because of resistance to the first-line antimonial drugs. We aimed to evaluate the differences in organelle changes of cultivated promastigotes obtained from skin lesions of sensitive and unresponsive isolates to meglumine antimoniate (Glucantime) by electron microscopy. Material and Methods: This study was done in Bam city, southeastern Iran, in which the incidence of disease has sharply increased since the earthquake in 2003. The samples were taken from 66 patients who were referred to the cutaneous leishmaniasis (CL) treatment center in Bam. A questionnaire was completed for each individual, recording their demographic characteristics and CL status. The scraping smears provided from the edge of active lesions with sterile blades were fixed with methanol, stained by Giemsa, and examined under a compound light microscope for amastigote form simultaneously. To prepare the specimens for transmission electron imaging, promastigotes were centrifuged and resuspened. Results: Transmission electron microscopic study of the cultivated promastigotes revealed that there were alterations in the organelles and structures of sensitive isolates compared with unresponsive and standard ones. Organelles and structures such as mitochondria, kinetoplast, microtubules, cytoplasmic vacuoles, plasma membrane and vesicles were studied. The alterations such as disintegration of kinetoplast into thin filaments and condensation of kinetoplast DNA core, changes in size, number and location of vesicles and microtubules were observed. We noted intense cytoplasmic vacuolization, and considerable swelling of mitochondria. Conclusion: The significance and relevance of these changes might help understand drug resistance patterns and help localize the best target site for inactivating the organism.

To examine the practical limits and effects of low voltage operation, studies of electron beam lithography (EBL) in the low (few keV) to ultra-low (E < 500eV) energy range, employing commonly used resists such as PMMA was done, and the results were compared to those from conventional high voltage processing. The direct writing was performed at low energies by our homemade scan generator and a Schottky field emission gun scanning electron microscope (SEM), used in cathode-lens mode for ultra-low voltage operation. The exposure characteristics and sensitivity of the system at these energies have been investigated using an advanced Monte Carlo simulation method. Our modeling of the lithographic process showed a significant increase in resolution and process latitude for thinner resists.

In 1981 A. N. Broers suggested that the spatial limit of direct writing electron beam lithography (DWEBL) would be limited to ~10 nm by the laterally scattered fast secondary electrons (FSE) even in atomically thin resist. One possible solution to this restriction would be to use low- or ultralow-energy electrons. Experiments and simulations have been carried out to quantify the contribution of FSE to the energy deposition that results in exposure of the resist over high-beam energies. To examine the effects of FSE on low-voltage operations, studies of electron-beam lithography (EBL) in the low- to ultralow-energy range, employing commonly used resists such as PMMA, were performed, and the results were compared to those from conventional high-voltage processing. DWEBL was performed in a Schottky field emission gun scanning electron microscope (SEM), used in cathode-lens mode for ultralow-voltage operation. The exposure characteristics and sensitivity of the system at these energies have been investigated using Monte Carlo simulation methods. Saturation doses were calculated at low energies, which would give a useful condition to target for routine exposure because it ensures the critical dimensions will not be affected by any random changes in beam intensity.